The loss of a lower extremity, even by careful surgical amputation, has profound physical and psychological consequences to the patient. It has long been known to remedy some of these consequences by providing a permanent prosthetic device to restore to the patient part of the function once performed by the lost limb. It is now generally accepted, however, that early post-operative weight bearing may be extremely valuable in both the physical and psychological rehabilitation of the amputee. By resuming ambulation with partial or full weight-bearing at an early stage, postural reflexes can be maintained, even while the residual stump is healing and being readied for a definitive fitting of a permanent prosthetic device.
Many advantages are offered by fitting a prosthetic device immediately after amputation. These include early ambulation, more rapid healing of the amputation site, decreased post-operative pain and edema of the stump, shorter hospitalization times, earlier fitting of a definitive prosthesis and a general improvement of the physical condition of the patient by preventing hypostatic pneumonia, phlebothrombosis, disuse weakness and psychological depression. The immediate post-operative prosthetic device thus aids the amputation team (consisting of the surgeon, the physiatrist, the prosthetist and the physical therapist) in the efficient treatment of the amputee.
Until recently, the amputation site was treated post-operatively with disposable soft compressive dressings, non-removable rigid dressings, or with so-called removable rigid dressings made from a plaster or fiberglass cast. These last were considered "removable" because they could be pulled off of the stump and then replaced upon it after inspection of the stump.
Both the removable and non-removable rigid dressings permitted partial or full weight-bearing through a temporary prothesis until the amputation wound had healed. For example, some rigid dressings served as prostheses sockets to which temporary prosthetic supports were attached. Such constructions were disadvantageous, however, in that they required that the full weight of the patient be borne on the amputation stump, interfering with patient healing and making it painful for the patient to use the prosthetic device. This was true even of pneumatic dressings; while soft and removable, they were still used in conjunction with rigid sockets, and so put the full weight of the patient on the stump.
Moreover, prior prostheses formed by embedding supports in rigid dressings were unitary and inflexible, making them difficult for patients to use. A prosthetic device which is painful or difficult to use does not get used at all, to the detriment of the patient.
The prior rigid dressings had other drawbacks. For example, to allow inspection of the amputation wound, the so-called removable rigid dressings were merely pulled off the amputation stump, causing very great pain to the patient and generating so much friction as to traumatize the amputation wound and the skin of the stump. Even when a felt pad was positioned between the stump and the rigid cast, the intense pain of removal and replacement discouraged patients from having their wounds inspected daily. Daily inspection, of course, is an indispensable part of proper amputation patient care.
Another drawback arose from the fact that removable rigid dressings were generally applied immediately after the amputation operations, while the patients were still on the operating table. Application of plaster cast or glass fiber dressings detrimentally affected patients because of the great amount of heat evolved during the curing of the casts. The problem was of particular concern because residual limbs already experience compromised circulation, especially when amputations are performed for peripheral vascular disease.
Another drawback arose in the casting method for making rigid dressings. By their very nature, the casts of the rigid dressings were custom made, tediously fitted to the dimensions of a particular patient's stump at the time of the amputation operation. Such cast were not subject to reuse or adjustment, and required frequent replacement when stump dimensions changed, as the stump cured and the swelling of the stump decreased.
Yet another drawback to the use of rigid casts as post-operative dressings was the extensive expertise required for their proper application. Techniques of this type were available to patients only at special medical centers where experienced prosthetists were available. Proper technique was critical because localized pressure areas from wrinkles or faulty plastering technique could cause pressure sores or decubitus ulcers, delaying healing of the amputation wound or resulting in infection of the wound. Moreover, even though plaster casts with rigid support posts didn't provide for full weight bearing, alignment of the support on the stump was still very difficult.
Of course, since the rigid casts generally did not allow inspection of the amputation site on a daily basis, a high incidence of stump complications was possible, requiring even more frequent removal and replacement of the rigid cast. The patient was thus obligated to return to the special medical center on a repeated and continuing basis, until such time as a definitive prosthetic device could be fitted.
My copending U.S. patent application Ser. No. 408,884, filed Sep. 18, 1989, contains a more extensive historical background to these problems and is incorporated by reference herein. That application was directed to a removable, size-adjustable rigid dressing for placement around a patient's amputation stump, and a lower limb prosthetic assembly incorporating such a dressing, and solved many of the drawbacks noted above. However, my prior device was perhaps not as conducive to post-operative ambulation as might be desired. It is critical to the success of an immediate post-operative prosthetic assembly that it be comfortable and convenient to use; a prosthetic device that pains the patient or is a struggle to use will not be used at all, and the patient will fail to gain the benefit of the device. It would be desirable to make my earlier assembly and dressing easier to adjust and fit to a particular patient; to restrict the limb stump flop sometimes encountered with the use of the assembly; to provide an easier control over locking of the knee joints of the assembly; and to make the assembly and dressing more comfortable to use and reduce the chance of impairment of circulation at the ischial cleft of the patient using the device.
Accordingly, it is an object of the present invention to provide a cost effective, easy-to-fit prosthetic assembly which is prefabricated and adjustable to the different height and orientation requirements of individual patients.
It is also an object of the present invention to provide a prosthetic assembly useful with a variety of amputation stumps yet which allows full weight-bearing within the first few hours or days after the amputation surgery, obviating any weight-bearing on painful and swollen amputation stumps, or on fresh or unhealed amputation wounds, without compromise of wound healing, skin integrity or circulation in the residual limb.
It is a further object of the present invention to provide a prosthetic assembly having an independent removable dressing, one whose ease of application obviates the need for the extreme degree of training required for the application of prior rigid cast dressings, but which in use achieves full ischial weight-bearing without compromising healing of the amputation wound.